Company Expects to Initiate a Phase 1/2 Study for ALN-XDH in Gout in Early 2022, with Initial Human Data in Late 2022

CAMBRIDGE, MA, USA I December 20, 2021 I Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), the leading RNAi therapeutics company, announced today that the Company has submitted a clinical trial authorization (CTA) application to The Medicines and Healthcare Products Regulatory Agency (MHRA) in the United Kingdom to initiate a Phase 1/2 study of ALN-XDH, an investigational RNAi therapeutic targeting xanthine dehydrogenase (XDH) for the treatment of gout. Upon obtaining MHRA approval, the Company plans to initiate a Phase 1/2 study in healthy volunteers and in patients with gout in early 2022, with initial human data expected in late 2022.

“We are excited to advance our ALN-XDH program to the clinic in light of the unmet need in gout, a chronic debilitating condition accompanied by acute inflammatory attacks. We believe the existing treatment landscape for gout has substantial limitations attributed to an incomplete response to standard of care, tolerability issues, and poor patient convenience. As a result, the majority of patients are untreated, cannot adhere to prescribed therapy, or do not reach target uric acid levels,” said Neil Wallace, Program Leader for the ALN-XDH program at Alnylam. “We believe ALN-XDH has the potential to address key unmet needs for gout patients, through potent urate-lowering effects achieved with infrequent dosing, which could potentially lead to a reduction of flares and other disease manifestations.”

ALN-XDH is a wholly owned, prevalent disease asset in the Alnylam clinical development portfolio.


ALN-XDH is an investigational, subcutaneously administered RNAi therapeutic targeting xanthine dehydrogenase (XDH) in development for the treatment of gout. Reducing XDH with an RNAi therapeutic is expected to result in potent urate lowering, essential in preventing gout-associated flares and managing the disease. ALN-XDH utilizes Alnylam’s Enhanced Stabilization Chemistry Plus (ESC+) GalNAc-conjugate technology, which enables subcutaneous dosing with increased selectivity and a wide therapeutic index. The safety and efficacy of ALN-XDH have not been evaluated by the FDA, EMA, or any other health authority.

About Gout

Gout is the most common form of inflammatory arthritis, impacting 14-18 million individuals across the US, Europe, and Japan. It is caused by the accumulation of uric acid crystals in joints and is accompanied by a number of debilitating clinical manifestations including edema, inflammatory arthropathy, pain, tophi, joint destruction and, in some patients, chronic kidney disease. The current standard of care for gout has substantial limitations including side effects, inadequate reduction of uric acid levels, increased risk of kidney stones, immunogenicity, and potentially increased cardiovascular risk. Many treatments require daily oral therapy even during asymptomatic periods. As a result, the majority of patients are untreated, cannot adhere to prescribed therapy, or do not reach target uric acid levels.

About RNAi

RNAi (RNA interference) is a natural cellular process of gene silencing that represents one of the most promising and rapidly advancing frontiers in biology and drug development today. Its discovery has been heralded as “a major scientific breakthrough that happens once every decade or so,” and was recognized with the award of the 2006 Nobel Prize for Physiology or Medicine. By harnessing the natural biological process of RNAi occurring in our cells, a new class of medicines, known as RNAi therapeutics, is now a reality. Small interfering RNA (siRNA), the molecules that mediate RNAi and comprise Alnylam’s RNAi therapeutic platform, function upstream of today’s medicines by potently silencing messenger RNA (mRNA) – the genetic precursors – that encode for disease-causing or disease pathway proteins, thus preventing them from being made. This is a revolutionary approach with the potential to transform the care of patients with genetic and other diseases.

About Alnylam Pharmaceuticals

Alnylam (Nasdaq: ALNY) is leading the translation of RNA interference (RNAi) into a whole new class of innovative medicines with the potential to transform the lives of people afflicted with rare genetic, cardio-metabolic, hepatic infectious, and central nervous system (CNS)/ocular diseases. Based on Nobel Prize-winning science, RNAi therapeutics represent a powerful, clinically validated approach for the treatment of a wide range of severe and debilitating diseases. Founded in 2002, Alnylam is delivering on a bold vision to turn scientific possibility into reality, with a robust RNAi therapeutics platform. Alnylam’s commercial RNAi therapeutic products are ONPATTRO® (patisiran), GIVLAARI® (givosiran), OXLUMO® (lumasiran), and Leqvio® (inclisiran) being developed and commercialized by Alnylam’s partner Novartis. Alnylam has a deep pipeline of investigational medicines, including six product candidates that are in late-stage development. Alnylam is executing on its “Alnylam P5x25” strategy to deliver transformative medicines in both rare and common diseases benefiting patients around the world through sustainable innovation and exceptional financial performance, resulting in a leading biotech profile. Alnylam is headquartered in Cambridge, MA. For more information about our people, science and pipeline, please visit and engage with us on Twitter at @Alnylam, on LinkedIn, or on Instagram.

SOURCE: Alnylam Pharmaceuticals